1. Field of the Invention
The present invention relates to a method of recycling a developing cartridge used in an image forming device, such as a laser printer.
2. Description of the Related Art
Electrophotographic image forming devices, such as laser printers, are normally provided with a detachable developing cartridge. The developing cartridge is filled with toner, and replaced once the toner runs out.
Explained in more detail, the developing cartridge is partitioned into a toner chamber and a developing chamber. The toner chamber is filled with toner and includes an agitator. A supply roller and a developing roller are disposed in contact with each other in the developing chamber. A layer thickness regulating blade is disposed in the developing chamber in pressing contact with the surface of the developing roller.
When mounted into the laser printer, the developing cartridge is brought into connection with gears of the laser printer for providing drive force to rotate the various components of the developing cartridge. When the agitator rotates, it conveys toner from the toner chamber into the developing chamber. When the supply roller rotates, it supplies the toner in the developing chamber to the developing roller. As the toner passes from the supply roller to the developing roller, the toner is triboelectrically charged between the supply roller and the developing roller. Further, as the developing roller rotates, the toner that was supplied onto its surface passes between the developing roller and the layer thickness regulating blade. This regulates the toner layer to a fixed thickness on the surface of the developing roller.
The laser printer in which the development cartridge is used includes a photosensitive drum, components for forming electrostatic latent images on the surface of the photosensitive drum, a transfer roller that is disposed in confrontation with the photosensitive drum, and a sheet transport unit for transporting sheets in between the photosensitive drum and the transfer roller.
The developing cartridge is mounted in the laser printer so that the developing roller confronts the photosensitive drum. Rotation of the developing roller brings the toner on its surface into confrontation with the photosensitive drum. At this time, the toner moves onto an electrostatic latent image formed on the surface of the photosensitive drum, thereby developing the electrostatic latent image into a visible toner image. Rotation of the photosensitive drum moves the visible toner image into confrontation with the transfer roller. At this time, the sheet transport unit transports a sheet between the photosensitive drum and the transfer roller. Electric potential difference developed between the photosensitive drum and the transfer roller draws the visible toner image from the photosensitive drum onto the sheet. In this way, a desired toner image can be formed on the sheet.
When the developing cartridge runs out of toner, then the laser printer will indicate that toner has run out, to urge the user to replace the developing cartridge. The user removes the used developing cartridge and mounts a new developing cartridge in its place.
Up until recently, used developing cartridges were merely discarded. However, it is becoming more common to recycle empty developing cartridges by refilling them up with toner and using them again in a laser printer.
Emulsion polymerization toner, suspension polymerization toner, and other types of polymerization toner are being used more frequently in laser printers. The toner particles of polymerization toner are nearly spherical. This contrasts to the jagged shape of pulverized toner. The spherical-shaped particles of polymerization toner furnish polymerization toner with extremely high fluidity, so that images with extremely high quality can be produced.
A drawback of polymerization toner is that it can easily leak out from the developing cartridge because of its high fluidity. To prevent toner leaks from leaking out from between the developing roller and the casing of the developing cartridge, developing cartridges are provided with seal members at both axial ends of the developing roller, in sliding contact with the surface of the developing roller. However, the seals are abraded down during use of the developing cartridge. This reduces their ability to seal the polymerization toner within the developing cartridge. When the developing cartridge is recycled, the newly added polymerization toner can easily leak through gaps between the seal member and the developing roller to outside the developing cartridge. Therefore, the seal members must be exchanged when the development cartridge is refilled.
Further, the toner that enters in between the seal members and the developing roller can melt by frictional heat generated as the developing roller rotates. The melted toner cools and solidifies once the developing roller stops rotating. When the developing roller is next driven to rotate, the solidified toner can cut into the developing roller and the seal members, thereby quickly degrading the sealing ability of the seal members even further.
Also, the toner itself degrades during use of the developing cartridge. Such degraded toner can result in image fogging. When a used developing cartridge is refilled with toner while a great deal of toner still remains from the previous use, then image fogging can occur when the developing cartridge is reused to form images. In order to prevent this problem, the developing cartridge can be taken apart and cleaned to completely remove previously-used toner before refilling with fresh toner. However, this is extremely troublesome and can increase costs.
It is an objective of the present invention to provide a method of reusing a used developing device that enables easy refill with developing agent and achieving good image formation during reuse of the developing device.
Methods according to one aspect of the present invention are for refilling a used developing device with developing agent for developing electrostatic latent images. The developing device includes a holding chamber for holding developing agent, a port for accessing the holding chamber from outside the used developing device, and a developing agent bearing member that bears developing agent from the holding chamber.
To achieve the above-described objectives, according to one aspect of the present invention the port is opened to access the holding chamber. A type of previously-used developing agent that remains in the holding chamber from a preceding developing operation usage is determined. A type of developing agent that has a lower fluidity characteristic than the previously-used developing agent is determined. The fluidity characteristic represents fluidity of the developing agent. The holding chamber is refilled with the type of developing agent that has the lower fluidity characteristic. Then, the port is closed.
According to another aspect of the present invention, the port is opened to access the holding chamber. A type of previously-used developing agent that remains in the holding chamber from a preceding developing operation usage is determined. A type of developing agent that has a lower melting characteristic than the previously-used developing agent is designated. The melting characteristic represents ease at which the developing agent melts. The holding chamber is refilled with the type of developing agent that has the lower melting characteristic. Then the port is closed.
According to still another aspect of the present invention, the port is opened to access the holding chamber. Residual developing agent is removed from a preceding developing operation usage of the used developing device to an amount of 1.2 g or less per centimeter of the axial length of the developing agent bearing member. The holding chamber is refilled with developing agent. The port is closed.